Expert: Predicting volcanoes not yet reality

Bob Tilling, a vulcanologist with the U.S. Geological Survey, says while scientists can learn from each eruption, that data doesn't necessarily translate from one mountain to another.

By Marsha WaltonCNN Sci-Tech

(CNN) --Some small tremors are still being felt around Goma, Congo, one week after the Nyiragongo volcano erupted in Africa.

While aid workers deal with the difficult logistics of getting food and fresh water to about 400,000 people, vulcanologists around the world are compiling data on the latest eruption of this relatively new volcano, which has probably been active for a few thousand years. Small earthquakes are common for days after an eruption.

Both instruments and scientists monitor many volcanoes in Japan, France, Italy, and the United States closely, but the economic situation in Congo and many other places around the world make that impossible. Nyiragongo did not have extensive equipment set up to track its activity.

With the proper equipment, scientists can pick up precursors to an eruption, said Bob Tilling, a vulcanologist with the United States Geological Survey (USGS).

"Most volcanic eruptions are preceded by earthquakes, we get a swelling of the ground, we get cracks, we get more gases coming out," he said.

Some of the equipment needed to keep track of a mountain's behavior include tilt meters to measure surface movements, crack meters to measure fissures or breaks in the mountain wall, and seismic sensors to monitor for earthquakes. There are also thermal and infrared sensors onboard satellites to scan the Earth for hot spots.

"Even though we cannot predict a day or a week when it will erupt, we can say it is 'restless,' that something is going on, and local officials can be advised and make contingency plans," Tilling said from the USGS in Menlo Park, California.

When is it all over?

While the technology is getting better for forecasting non-explosive eruptions, very few of about 550 active volcanoes around the world are being monitored closely. And, says Tilling, while scientists can learn from each eruption, that data doesn't necessarily translate from one mountain to another.

Most volcanoes are located where tectonic plates are pulling apart or coming together.

"Each volcano behaves individually, they're like people, they have their own personalities and behavior," said Tilling.

And just as difficult as predicting when a volcano will erupt, is determining when the eruption is really over.

"The instruments we have tell us what the volcano is doing now. It does not give us a real basis for what it might do two or three weeks from now," he said.

Tilling says he is optimistic that better instruments and more comprehensive study of past eruptions will improve forecasting abilities, but he says there's no magic bullet in the near future that will make early warnings of eruptions a reality.